Week One

Prepare Your Body to Work

To get your metabolism moving, you need to get your muscles working. “Muscle naturally burns calories, so the more of it you have, the more calories you’ll burn at rest,” Holland says. Aim for 4 days of resistance training this week, along with 30 to 45 minutes of cardio training on the off days. Use these tips to maximize your strength building in this short amount of time so that you can build your foundation fast.

Power Your Pump

Holland suggests adding weight and lowering your reps when lifting. “It’s better for strength building because you’re working power versus endurance,” he says. You’ll tax your muscles more, making this more efficient for muscle building in a tight time frame. Women, thankfully, have little testosterone, the hormone responsible for bulking up. But some women have more of it than others. If you tend to be stocky, stick to your regular amount of weight, says trainer Brenda Powell, general manager of the Institute of Human Performance in Boca Raton, Florida. But if you have an average build, you should lift weights heavy enough that you can only complete eight reps, and keep adding weight with each set until you can only do four or five reps. Try this every other strength session to keep your muscles challenged.

Push Your Muscles

Organize your strength sessions so that you have 2 days of them back to back. “You’ll work your muscles harder — almost shock them into shape,” Holland says. “When you break them down more, they’ll repair and build up more.” For example, lift weights on Monday, Tuesday, Thursday, and Saturday. You’ll have enough rest time on Wednesday, Friday, and Sunday to recover, but if you’re sore, do different exercises to challenge your muscles from different angles. You’ll actually benefit from doing a range of exercises since your muscles will constantly be challenged to adapt, and you’ll burn more calories while they’re forced to work harder.

Stay Fueled

Powell says your insulin levels drop during intense exercise (anything where you’re working at 75 percent of your maximum heart rate, such as a spinning class). When your insulin levels become irregular, your body produces cortisol, a stress hormone that breaks down muscle and has been linked to belly fat production. You need to replenish your glycogen stores as you work to regulate your insulin levels. “Anytime you do multiple sets, your glycogen levels drop 40 percent,” Powell says. Sip a sports drink during intense exercise. Don’t worry about the calories: An 8-ounce serving of Gatorade contains just 50 of them. And though water is fine for moderate exercise, for intense sessions you’ll need the calories and electrolytes to keep your muscles and metabolism primed.

Make Use of the Magic Window

The 45-minute period after exercise is the best time for your body to metabolize nutrients, Powell says. Your metabolism is already elevated from your workout, and when you refuel correctly, you can keep the fire burning. Eat something that has carbs to restore glycogen and protein to help build muscle. Go for a grilled chicken sandwich or yogurt with almonds and fruit. It’s ideal if you can eat within the first 20 minutes after exercise since you’ll be able to regulate your blood sugar faster. “You can also eat one-third of your daily calories within the 3 hours postexercise, because your body is in high-burn mode, and will metabolize the calories faster,” Powell says.

Mix Your Meals

Always mix protein, carbs, and fat when you eat, says Ann Yelmokas McDermott, Ph.D., a nutrition scientist at Tufts University. You need the blend to fuel your body and stay satiated. Whenever you have one group alone, you’re more likely to feel hungrier sooner and consume more food. And don’t fear healthy fats. “They take longer to break down in the gut, so you’ll feel fuller longer and will end up consuming less calories,” McDermott says. Instead of spooning fat-free yogurt, for example, choose low-fat. Stir-fry veggies in olive oil, or spread peanut butter on a bagel.

Week Two

Max Your Metabolism

Now that you’ve gotten into a groove and built some muscle, you should increase your intensity to further boost your metabolism. To start, swap one of your strength workouts for an extra cardio day to give yourself more time to burn calories at a higher level, and add a session of intervals to make your cardio more intense. (For example, you could now make Tuesday a cardio day instead of strength.)

Flood Yourself

Drinking more water can maximize your metabolism. Researchers at the University of Utah found that dehydration (from sweating) can slow your resting metabolism (RMR) by 2 percent, which, if your RMR is 1,500 calories, amounts to 30 unburned calories per day. In another study they found that drinking 12 8-ounce glasses of water raises metabolism higher than drinking four or eight 8-ounce glasses. “Drinking more water also increases energy, along with the desire to exercise,” says researcher Wayne Askew, Ph.D., professor of nutrition at the University of Utah. If you can drink two tall bottles of water a day, you’ll help your metabolism peak.

Stop and Go

Instead of jogging for half an hour, do intervals. Sprint for a minute, and then rest for a minute. The change in intensity will increase your metabolism and allow you to work harder while giving you time to breathe. Holland suggests using dice to make your intervals interesting. If using one die, or even two, multiply the number you roll by 10, and sprint for that many seconds (then rest for double that amount). You can also use the dice for circuit intervals during your weight routine. If you roll an odd number, do crunches — and use the number you roll to get your reps. If you get an even number, do squats or pushups. It’s a simple way to keep your workout varied and keep yourself moving. For extra fat burning, Powell says to add intervals after 45 minutes of strength training. She suggests doing three to five sets of 1-minute hard intervals, with 2-minute recovery periods.

Rest Actively

When you rest between sets, stay active to keep your heart rate up. Work a different muscle group — if you’re doing lunges, do pushups between sets. You could also add cardio by performing jumping jacks or jogging in place. A cumulative 10 minutes of these exercises during rest will torch an extra 85 calories.

Add Protein

Increase your protein intake to rev your metabolism. “The body has to work harder to process it because it contains nitrogen, which is metabolically expensive,” Dr. Deitrick says. But eating too much protein can make you tired because your body is using its energy to digest. General RDA dietary requirements include 0.4 grams of protein for every pound of body weight. For a 140-pound woman, that’s 56 g. Dr. Deitrick suggests temporarily adding an extra 30 g of protein to your diet, which will make your body work harder and burn more calories. You could add a half-cup of cottage cheese (15 g) and 8 ounces of low-fat yogurt (11 g), or 8 ounces of skim milk (8 g) and 3 ounces of tuna (22 g).

Sleep Well

Get at least 6 hours of sleep each night. “Your body releases growth hormones after 6 hours of sleep, which is when your muscles actually get toned,” Holland says. “If you get enough rest to release those muscle-toning hormones, you’ll be able to push harder the next day.” It’s also important to add a slow day — possibly midweek — to give your muscles a break and a chance to grow even more. Go for a long walk or an easy jog instead of your usual tough routine.

Week Three

Kick in the Afterburners

Now’s the time to burn as many calories as you can in your workout. Swap out another strength session and replace it with heavy-duty cardio, which will raise your heart rate. At this point, your time is best spent doing cardio since you’ve already built some muscle during weeks 1 and 2.

Try Not to Talk

If you can hold a conversation for 20 minutes while jogging, you’re fine. But to speed up your metabolism, Dr. Deitrick advises going beyond your comfort zone, to the point where you can’t talk. Use this as a way to raise interval intensity levels, too. Go hard enough so that you can’t talk for 2 minutes, and slow down so that you can chat for 2 minutes. To burn the most fat and calories, go as hard as you can for as long as you can.

Add Resistance

Amplify your intervals by adding resistance to make them harder. Holland suggests hill repeats — sprint up a hill and walk back down. Do five reps after a 5- to 10-minute warmup. You can also increase the incline on your treadmill or crank the knob on your spinning bike.

Extend Your Intervals

Do tempo runs, which are essentially long intervals, to maximize your calorie burn both during and after your workout. (The increased intensity keeps your metabolism higher for a longer post-exercise period.) Holland suggests running hard for 5 minutes and then jogging for 5 minutes. If you can, push yourself to go harder than your typical pace for 15 minutes. Incentive: If you run for 15 minutes at 7 mph (try this on a treadmill to note your speed), you’ll burn about 180 calories versus the 110 you’d burn if you were jogging for the same time (based on a 140-pound woman). Jog for 10 minutes to warm up before your tempo run, and then for 10 minutes postrun to cool down.

Control Out-of-Control Hunger

When you’re exercising harder, you’ll feel hungrier postworkout. Dr. McDermott suggests drinking a protein and fruit smoothie after your workouts. Store peeled bananas in the freezer (in Ziploc baggies) and buy flash-frozen berries. Once you get home, blend a banana, some berries, 8 ounces of plain low-fat yogurt, and a cup of low-fat milk to make an instant frozen smoothie — and instant gratification.

Keep Your Body Wondering

“Play with your work-to-rest ratios when doing intervals to keep your body guessing,” says Gunnar Peterson, a celebrity trainer in Los Angeles. When your body can’t adapt to your plan, it’s forced to work harder, so you’re always working in your fat-burning capacity. Peterson suggests “undulating” your intervals: For example, run or pedal hard for 2 minutes, and then rest for 30 seconds. Go hard again for 2 minutes, and then rest for 1 minute. Extend your rest periods by 30 seconds until you reach 2 minutes, and then work your way back to 30-second rest periods, clipping 30 seconds at a time.